F15 can get close enough.
The Soviets used dedicated high altitude interceptors with high sensitive detonators on HE rounds. It was still a problem to kill one.
F-15 may try to fire a heat seeking missile on a side of the balloon exposed to sunlight but I wouldn’t bet too much on a success.
I think USAF would have solved it if it could.
To do what? Ask the balloon for it's preferred personal pronoun? The fact is that we didn't shoot it down and we aren't going to shoot it down. The media excuses this morning are are just pathetic. "Well, even if it's spying, it's not doing any harm..."